Final answer:
The correct ohmic value for a resistor marked 180 K is 180,000 ohms. 'K' represents kilo, and the resistance must be greater than any of the individual resistors when connected in series.
Step-by-step explanation:
The ohmic value of a resistor that is marked 180 K would be 180,000 ohms. The 'K' in 180 K stands for kilo, which is a metric prefix meaning thousand. Therefore, you must multiply 180 by 1,000 to find the resistance in ohms.
Similarly, when calculating the maximum resistance possible given a resistor of 100 ohms and a resistor of 40 ohms, you get 140 ohms if you are connecting them in series. However, if they are connected in parallel, the equivalent resistance would be lower than the smallest resistor (which doesn't apply here as we are looking for the maximum resistance).
In terms of safety and reasonability, series connections of resistors simply add up their resistances, and there are no negative resistances in practical scenarios. Therefore, series resistance must be greater than any of the individual resistors.